from django.contrib.auth.models import User
from django.db import models
from django.urls import reverse
import uuid
from datetime import date

class Genre(models.Model):

    name = models.CharField(max_length = 200, help_text = " Enter a book genre")

    def __str__(self):
        return self.name

class Book(models.Model):

    title = models.CharField(max_length = 200)
    author = models.ForeignKey('Author', on_delete = models.SET_NULL, null = True)
    summary = models.TextField(max_length = 1000, help_text = "Brief description of this book")
    isbn = models.CharField(max_length = 13)
    genre = models.ManyToManyField(Genre, help_text = "Select a genre for this book")

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse('book-detail', args = [self.id])
    
    def display_genre(self):
        return ','.join([genre.name for genre in self.genre.all()[:3]])
    display_genre.short_description = 'Genre'

class BookInstance(models.Model):

    id = models.UUIDField(primary_key = True, default = uuid.uuid4)
    book = models.ForeignKey('Book', on_delete = models.SET_NULL, null = True)
    imprint = models.CharField(max_length = 200)
    due_back = models.DateField(null = True, blank = True)
    borrower = models.ForeignKey(User, on_delete = models.SET_NULL, null = True, blank = True)

    LOAN_STATUS = (
        ('m', 'Maintenance'),
        ('o', 'On loan'),
        ('a', 'Available'),
        ('r', 'Reserved'),
    )

    status = models.CharField(max_length = 1, choices = LOAN_STATUS, blank = True, default = 'm')

    @property
    def is_overdue(self):
        if self.due_back and date.today() > self.due_back:
            return True
        return False

    class Meta:
        ordering = ["due_back"]
    
    def __str__(self):
        return '{id} ({title})'.format(id = self.id, title = self.book.title)

class Author(models.Model):
    first_name = models.CharField(max_length = 100)
    last_name = models.CharField(max_length = 100) 
    date_of_birth = models.DateField(null = True, blank = True)
    date_of_death = models.DateField(null = True, blank = True)

    def get_absolute_url(self):
        return reverse('author-detail', args = [str(self.id)])
    
    def __str__(self):
        return '{0}, {1}'.format(self.last_name, self.first_name)

    class Meta:
        ordering = ['id']
    